Bridge construction



(No Model.)

H. E. MERTENS. BRIDGE CONSTRUCTION.

No. 424,427. Patented Mar. 25, 1890...

XIIIIIIIIIW ill elzimt Zzzzyl ZZZeziz'zs.

N. Prrzns, PMto-Lilhcgmphor, Washington. In:

UNITED STATES PATENT OFFICE.

HENRY E. MERTENS, OF ST. PAUL, MINNESOTA.

BRIDGE CONSTRUCTION.

SPECIFICATION forming part of Letters Patent No. 424,427, dated March25, 1890.

Application filed October 15, 1889. Serial No. 327,132. (No model.)

To all whom it may concern.-

Be it known that I, HENRY E. MERTENS, a citizen of the United States,residing at St. Paul, in the county of Ramsey and State ofMinnesota,have invented certain new and useful Improvements in theConstruction of Bridges; and I do declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame, reference being had to the accompanying drawings, and to thefigures of reference marked thereon, which form a part of thisspecification.

This invention relates to the construction of bridges; and it consists,generally, in the means employed for supporting the floorbeams withreference to the posts and in the connection between the longitudinalstringers and floor-beams.

The floor-beams of through-bridges have commonly been supported eitherby riveting directly to the vertical posts or by suspending thefloor-beams below the lower chords of the bridge by means of hangers. YVhen supported in the first-mentioned manner, the floor-beam by beingloaded will have its upper flange shortened and its lower flangelengthened, and the parts of the posts riveted to the ends of thefloor-beams necessarily fol- I low this movement, whereby the posts willbe deflected, and on account of the deflection will require a greatersection or more material to withstand, in addition to the naturalstrain, the strain involved by the bending of the post, than would beotherwise required. Moreover, when so constructed the pull against therivet-heads in the upper part of the connection between post and beam isliable to tear off the rivet-heads and render the whole constructiondangerous. The same result also occurs from riveting the stringers tothe floor-beams, as is the common method of construction. The load uponthe stringers causes the upper flange to be shortened and the lowerflange to be lengthened, thereby exerting a pulling force upon the upperrivetheads of the connection and rendering a detaching of the heads ofthe rivets possible.

In the case of suspended floor-beams there is generally a little spaceleft between the lower end of the post and the top of the beam asallowance for the curvature of the beam under load, which allows thebeam to jump to a greater or less extent.

My invention is designed to obviate the disadvantages herein set forth;and it consists in the general construction employed for this purposeand in various features of detail, hereinafter set forth.

The invention is illustrated in the accompanying drawings, in which--Figure l is a partial cross-section of a portion of a bridge,illustrating the means employed for supporting the floor-beams andsupporting the stringers with reference thereto; Fig. 2, a sideelevation of one of the vertical posts, showing in dotted lines themeans employed for supporting the floorbeams; Fig. 3, a top view of theend of a fioorbeam, showing the post in cross-section; Fig. 4-, across-section of the post in a plane indicated by the line 4 4 in Fig. 2Fig. 5, an under side view of the plate which is riveted to the lowerend of the post and the floor-beam, to which plate the lateral rods areattached; and Fig. 6, a cross-section of the floor-beam, showing themeans employed for supporting the stringers thereto.

In the drawings, 1 is a vertical post of the form commonly used inbridges, consisting, mainly, of two channels connected by latticework,though the form is not material, having near its lower end the pin 2, towhich are attached the several eye-bars 3 3, forming the lower chord andthe diagonals of the bridge.

' Between the two sides of the post is formed a bracket 4, consisting ofa vertical plate 5 and angle-plates 6 6, riveted together. The bracket,as an equivalent construction, may be formed of an I-beam or twochannel-plates, with or without thickening-plates on one or both sides.The bracket thus formed constitutes a support for the floor-beam 7,which rests directly thereupon and is retained in place against lateraldisplacement by means of guide-plates 8 8, riveted either to the sidesof the bracket and extending a short distance above the edge of thebeam, as shown in the drawings, or riveted to the floor-beam andextending a short distance over the sides of the bracket. The bracketmay rest directly upon the pin and be held in position by guidesattached to the post, or it may be only riveted to the post in such amanner as to withstand the total load at the end of the floor-beam; orit may rest directly upon the pin and be held in position by beingriveted to the post, which last arrangement is shown in the drawing.

The floor-beam 7 is of usual form, consisting of a flat plate of metal,constituting the web, and angle-plates attached to the top and bottom ofthe plate to form the flanges.

For the purpose of having the lateral strain pass through the lowerflange of the floorbeam, and by this method decrease the tension in thelower flange of the beam, Iconnect the floor-beam with the bottom plate14. To give space for the ends of the lower chordbars, the lower partsof the ends of the beam are cut away and the ends of the lower flangeplates bent up accordingly. To replace the material cut away from thefloor-beam, by which the same is weakened, the floor-beam is againstrengthened at the end by means of two plates 9, riveted rigidly to thesame, and the top and bottom flange-plates at the points where they meetthe thickening-plates 9 are bent over the same. At the extreme ends ofthe floor-beam two more thickening-plates 10 are riveted to the threealready existing plates, so as to give sufficient stiffness againstbuckling of the Web and producing a sufficient bearing-surface at thebottom of the floor-beam. The lower end of this group of five platesrests upon the center of the bracket. The portion of the web extendingbelow the lower flange-angles of the floor-beam is stiffened at itslower end by two angle-plates riveted by their vertical legs to the weband by their horizontal legs to the lateral plate 14.

Instead of having a portion of the web of the floor-beam cut away, asabove mentioned, to give space for the lower chord-bars, it might beless expensive to have the end of the web of the floor-beam terminate atthe point Where the cutting away begins, and shorter pieces of suitablesize spliced to the ends of the web by the two thickening-plates 9 9, asshown in the drawings. It will be observed that the load upon thefloor-beam 7 is borne directly by the bracket. The beam is not at anypoint supported by bolts or rivets, but is held in position againstlateral displacement at the bottom by its connection with the lateralplate 14 at the point of support by guideplates and at the top by meansof an angleplate 11, riveted to the post and secured to the beam in sucha manner as to admit of the longitudinal movement of the same under loadby means of bolts 12 12, passing through the angle-plate and throughslots 13 in the horizontal legs of the upper floor-beam flanges. It willbe noticed that upon the curvature of the beam, which takes place underload, the upper flange of the beam is shortened relatively to thedistance between opposite posts, the slots 13 allowing a play of thebeam upon the bolts 12 for that purpose. At the same time the portion ofthe beam which rests upon the brackets 4 is free to slide thereupon,thus permitting the beam to yield to any extent without the exertion ofany degree of side strain upon the post.

The stringers or longitudinal beams connecting the adjacent cross-beamsare supported in a manner substantially similar in principle. To thesides of the floor-beams 7, at the points where the stringers are to belocated, are riveted thickening-plates for the purpose of stiffening theweb and distributing the load borne by the stringers over the wholeheight of the beam. To these thickeningplates and the floor-beam web areriveted the brackets 16, conveniently formed of several angle andstiffening plates riveted strongly together and to the floor-beam andbearing on the lower flange of the floor-beam. these brackets rest theends of the stringers, each end being properly strengthened by means ofsuitable stiifening-plates 18 and angle-plates 19, riveted thereto insuch a manner that the outer faces of the angle-plates shall lie closelyagainst the thickening-plates 20 of the floor-beam.

Through the outwardly-extending legs of the angle-plates 19 and the beamare inserted bolts 21 21, for the purpose of retaining the stringers inproper position laterally. It is to be understood that these bolts arenot intended to carry any part of the load, and on this account, and forreasons hereinafter stated, are placed at some distance from the web ofthe stringer and preferably as near as possible to the outer edge of theflange. The object of this construction is to allow a slight parting ofthe upper edge of the stringer from the floor-beam by a slight bendingof the angle-legs between the points of attachment or the bolts 21 whenthe curvature of the stringer under load takes place. The entire load isborne by the brackets, the function of the bolts being, as stated, topreserve the proper lateral position of the stringer.

In addition to overcoming the disadvantages above set forth as met within. previous methods of construction, it may be mentioned as aconstructive advantage possessed by this invention as compared withfloor-beams riveted to the posts that a considerable amount of fieldriveting will be saved, and the well known superiority of shop rivetingover field- Upon work renders this feature of great imporsame, and abracket located above the lower chord-pin and riveted to the posts,which bracket forms a bearing-surface for the floorbeams to rest upon,substantially as specified, whereby field-riveting for supporting thefloor-beam is entirely avoided.

2. In a bridge, the combination of chords,

diagonals, and posts, pin passing through the same, and a bracketadapted to form a seat or a bearing-surface for the end of the floorbeamWithout being rigidly connected to the latter, which bracket restsdirectly on the pin, substantially as and for the purpose hereinspecified.

3. In a bridge, the combination of chords, diagonals, and posts, pinpassing through the same, and a bracket located above the lowerchord-pin and adapted to form a seat for the end of the floor-beam, andguides carried either by the bracket or by the end of the floor-beam andembracing the other of said parts, respectively, for the purpose ofretaining the bearing-surface of the beam in position laterally,substantially as specified.

4. In a bridge, the combination of vertical posts, lower chord-bars, anddiagonals, pin passing through the same, a bracket adapted to formatseat for the end of the floor-beam,

guides mounted either upon the bracket or upon the floor-beam, anangle-plate having one of its legs secured to the post and the otherresting upon the top of the fioor-beam,

and bolts passing through the horizontal leg of the angle-plateandthrough longitudinal slots in the flanges of the floor-beam,substantially as specified, whereby the floor-beam is restrained fromvertical and lateralunovement, but allowed a longitudinal play Withreference to the post.

5. A bridge having its cross-beams supported upon brackets, by Whichmeans the bending of the posts due to the curvature of the floor-beamWhen loaded, is avoided, and supporting-brackets attached to the web ofthe floor-beam for supporting the stringers, substantially as specified.

6. The combination, with the cross-beamsof a bridge, of brackets securedto the sides thereof, stringers resting upon said brackets, angle-platessecured to the ends of the stringers, and bolts passing through theextending legs of said angle-plates and the cross-beam at a distancefrom the Web of the stringers,

substantially as specified, whereby the curva

